Lyme borreliosis (LB), the 2nd most important emerging disease and most common vector-borne disease in the USA, is caused by infection with the spirochete, Borrelia burgdorferi. In Maryland, LB is spreading rapidly and increasing in incidence with reported cases doubling each year. Infection causes a characteristic rash and "flu-like" symptoms and chronic and recurrent arthritis, carditis and neurological abnormalities. LB is difficult to diagnose and it's treatment, particularly therapy of the chronic stages, remains uncertain and controversial. This project proposes to improve the quality of care in patients with LB by investigating differences in patient outcomes resulting from variations in antibiotic therapy. Inappropriate practice patterns will be identified and educational interventions to improve treatment practices will be evaluated. Using telephone interviews with reporting physicians and all LB cases reported to the Maryland Department of Health from 1993-1997, we will obtain information on antibiotics prescribed, patient compliance and adverse reactions to the drugs and clinical responses to different regimens for treating erythema migrans (EM), Lyme arthritis and other LB syndromes. Outcomes to be measured are: improvement or cure of illness and prevention of complications. The variables are patient-, disease- (e.g., confirmed or unconfirmed cases, stage of disease, disease syndrome) and treatment- related (e.g., drug, drug group, dose, length and route of therapy). During the first 3 years an estimated 1,200 to 1,600 cases of LB will be admitted to the study and followed for 3 years. In addition to simple contingency table analysis, multiple linear and logistic regression will be employed to hold the effects of confounders constant while computing risks and relative risks. During the 4th and 5th years two physician training interventions will be evaluated: the area-wide intervention will compare outputs from physicians practicing in part of the state who receive frequent mailings, lectures and provision of a LB "hotline" with those practicing in another area not having these. training exposures. In addition, a randomized study will compare the effects of a single intervention on half of the 800-to-1,000 physicians reporting LB cases during the first 3 years with the remaining 400-to-500. Effects of both interventions will be assessed by observations on clinical practice patterns and by pre- and termination-testing in the randomized study. Finally, algorithms will be constructed to assist Maryland physicians managing patients with suspected LB.